Welcome to the Earthdata User Forum! Here, subject matter experts from several NASA Distributed Active Archive Centers (DAAC) can discuss general questions, research needs and data applications. Users can query how to access, view and interpret the data.
by dem1 » Fri Aug 30, 2019 4:23 am America/New_York
Is it normal that the STRAYLIGHT flag for SeaWiFS is not consistent between GAC and MLAC products? For GAC it seems it is a simple fixed kernel around CLDICE but for MLAC it seems not the same algorithm. When removing CLDICE and STRAYLIGHT pixels, are MLAC products more contaminated by bad cloud border pixels than GAC products?
Yes, it is normal. For the full resolution data (MLAC), the code employs a correction for straylight based on pre-launch measurements. The GAC data were subsampled on-board the spacecraft and insufficient information is available to apply this correction, so a simplified masking is used.
by dem1 » Fri Aug 30, 2019 8:35 am America/New_York
If I'm not wrong other LAC sensors (MODIS/VIIRS) use simplified masking too? We observe that SeaWiFS MLAC are more contaminated by cloud borders than GAC and other LAC sensors, do you confirm this? So we are thinking to enlarge CLDICE+STRAYLIGHT for MLAC in our Level-3 processor. Do you know another way to remove contaminated cloud borders?
Yes, the only sensor for which we have a straylight correction is SeaWiFS. All others use a simple mask based on bright target adjacency. If you find contamination not captured by the default masking, yes you could increase the straylight mask.